Virtualization - Jul 2023 - [PATCH v1] vdpa: Complement vdpa_nl_policy for nlattr length check

On Sun, Jul 23, 2023 at 05:48:46PM +0800, Lin Ma wrote:
> 
> > Sure, that is another undergoing task I'm working on. If the
nlattr is parsed with
> > NL_VALIDATE_UNSPEC, any forgotten nlattr will be rejected, therefore
(which is the default
> > for modern nla_parse). 
> 
> For the general netlink interface, the deciding flag should be
genl_ops.validate defined in
> each ops. The default validate flag is strict, while the developer can
overwrite the flag
> with GENL_DONT_VALIDATE_STRICT to ease the validation. That is to say,
safer code should
> enforce NL_VALIDATE_STRICT by not overwriting the validate flag.
> 
> Regrads
> Lin

Oh I see.

It started here:

commit 33b347503f014ebf76257327cbc7001c6b721956
Author: Parav Pandit <parav at nvidia.com>
Date:   Tue Jan 5 12:32:00 2021 +0200

    vdpa: Define vdpa mgmt device, ops and a netlink interface

which did:

+               .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,


which was most likely just a copy paste from somewhere, right Parav?

and then everyone kept copying this around.

Parav, Eli can we drop these? There's a tiny chance of breaking something
but I feel there aren't that many users outside mlx5 yet, so if you
guys can test on mlx5 and confirm no breakage, I think we are good.

-- 
MST

On Sun, Jul 23, 2023 at 6:02?PM Michael S. Tsirkin <mst at redhat.com>
wrote:
>
> On Sun, Jul 23, 2023 at 05:48:46PM +0800, Lin Ma wrote:
> >
> > > Sure, that is another undergoing task I'm working on. If the
nlattr is parsed with
> > > NL_VALIDATE_UNSPEC, any forgotten nlattr will be rejected,
therefore (which is the default
> > > for modern nla_parse).
> >
> > For the general netlink interface, the deciding flag should be
genl_ops.validate defined in
> > each ops. The default validate flag is strict, while the developer can
overwrite the flag
> > with GENL_DONT_VALIDATE_STRICT to ease the validation. That is to say,
safer code should
> > enforce NL_VALIDATE_STRICT by not overwriting the validate flag.
> >
> > Regrads
> > Lin
>
>
> Oh I see.
>
> It started here:
>
> commit 33b347503f014ebf76257327cbc7001c6b721956
> Author: Parav Pandit <parav at nvidia.com>
> Date:   Tue Jan 5 12:32:00 2021 +0200
>
>     vdpa: Define vdpa mgmt device, ops and a netlink interface
>
> which did:
>
> +               .validate = GENL_DONT_VALIDATE_STRICT |
GENL_DONT_VALIDATE_DUMP,
>
>
> which was most likely just a copy paste from somewhere, right Parav?
>
> and then everyone kept copying this around.
>
> Parav, Eli can we drop these? There's a tiny chance of breaking
something
> but I feel there aren't that many users outside mlx5 yet, so if you
> guys can test on mlx5 and confirm no breakage, I think we are good.
Adding Dragos.

Thanks
>
> --
> MST
>